Protect PDF
Add a password and strong encryption so only people with the password can open your PDF.
Protect PDF online, free and private
Protecting a PDF means locking it behind a password so only the people you share it with can open it. It is the sensible step before you email a payslip, send a signed contract, or store bank statements in shared cloud storage — anyone who intercepts or stumbles onto the file sees nothing without the password. PDFToolz adds genuine AES-256 encryption, the same standard trusted for confidential documents, not a flimsy flag that any reader can ignore.
The entire process runs inside your browser. Your PDF is read into memory, encrypted locally with qpdf compiled to WebAssembly, and handed back as a download. The file — and the password you choose — are never uploaded to any server, so even the most sensitive paperwork stays entirely on your own device.
How to protect pdf in your browser
- 1
Select your PDF
Click ‘Select PDF file’ or drag your document onto the page. It loads straight into your browser — nothing is sent anywhere while you work.
- 2
Choose a password
Type the password that will be required to open the file. Pick something strong and memorable, because there is no reset link — if it is lost, the document cannot be recovered.
- 3
Encrypt the document
Press ‘Protect PDF’. qpdf running in WebAssembly encrypts every page with AES-256 locally, producing a new password-protected copy in seconds.
- 4
Download the protected file
Save the encrypted PDF to your device. From now on, any PDF reader will prompt for the password before it will display the contents.
Why use PDFToolz for this
Real AES-256 encryption
This is not a viewing restriction that software can politely skip — the file’s contents are genuinely encrypted with the AES-256 cipher. Without the correct password the document is unreadable, giving you the same protection level used for banking and legal records.
Your file and password stay private
Encryption happens with client-side WebAssembly, so neither the PDF nor the password ever leaves your computer. There is no server copy to breach and no record of your password anywhere but in your own memory.
Content preserved exactly
Only a security layer is added around your document; the pages themselves are untouched. Text stays selectable, fonts stay sharp, and images keep their original resolution once the file is unlocked.
Free, unlimited, and offline
Protect as many PDFs as you like with no account, watermark, or size cap. Because the work is local, the tool keeps working even after you disconnect from the internet.